Update elm implementation, fix keywords and metadata, merge eval

[asarhaddon]

Hello. The first commit updates the elm implementation for 0.19.1. The docker file describes my configuration but should probably be checked on an actual image. The two following commits fix the last failing optional tests. The two last commits should be part of #592, but required 0.19.1 for testing.

[asarhaddon]

The tests were passing on my machine, so they will probably also pass in an updated Docker image.